Summary: Only a small number of studies have empirically examined the determinants of the monitoring and enforcement performed by environmental regulators, and most of these have focused on industrial countries. In contrast, the authors empirically examine the determinants of enforcement in China. More precisely, they analyze the determinants of firms' relative bargaining power with local environmental authorities with respect to the enforcement of pollution charges. The authors show that private sector firms appear to have less bargaining power than state-owned enterprises. Contrary to earlier findings, they also show that firms facing adverse financial situations have more bargaining power than other firms and are more likely to pay smaller pollution charges than they should be paying. Finally, the authors show that the greater the social impact of a firm's emissions (as measured by complaints), the less bargaining power it has with local environmental authorities.